Window box storage unit



FIG. 1 is a top perspective view of the window box storage unit showing the new design;

FIG. 2 is a front elevation view thereof;

FIG. 3 is a right side elevation view thereof;

FIG. 4 is a rear elevation view thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom view thereof. 

CLAIM The ornamental design for a window box storage unit, as shown and described. 